Improvement in balanced slide-valves



Vcrate a plunger, D, which is top of, or to one Bn'NJM'uv BnAZEnLn, 1orsr. LoUiS, MISSOURI.

` ,',IMPRQl/ EMENT'IN BA-LANCED SLIDE-VALVES.

I v,Spieciicationforming partof Letters Patent To altwhom it amy-concem:i

,f Beit known that! I, BENJAMIN BRAZELLE, ofSt. Louis,vlVIissouri',.have invented Van ImprovedBalanc'ed Slide-Valve, of, whichthe following is a speeitication i This invention has for its object therelieving of slide-valves for steam-engines of friction, and achievesthe advantageous-results from the use of a balanced slide-valve.

The constructive principle of this invention is based upon the obtainingof a perfect balance or equilibrium by means of unequal pressures actingupon unequal areas, and as now Will more fully appear.

Of the drawing, Figure 1 is a Sectional elevation on line a: m of Fig.2. Fig. 2 is a top sectional plan on line w' w' of Fig. 1. Fig. 3 is apart side elevation, showing lever-connection with plunger-heads, Fig.44 being a bottom plan of slide-valve.

A represents the cylinder. B, Fig. 2, is the induction-port. b b1, Figs.l and 2, are the steam -inlet ports, which communicate by transverseports b2 b3 to the valve-seat. b4 b5 are the main steam-ports, thatserve alternately to admit steam to piston and exhaust from cylinder;B', Fig. 2, being the exhaustport. In steam-chest is the usualslide-valve C, having the three D-chambers or cores c c1 c2. The valvecontrols the ports b2 b3, and main ports b4 b5. rlhus, when valve is inthe position as shown in Fig. 1, the core c covers the port b3, whilethe opposite core 0l covers ports b2 b4, establishing steam-connectionto that end of cylinder, the center core c2 establishingexhaust-connection by covering port b5 and exhaust B', and vice versawhen the reverse stroke of piston takes place.

To carry out the principle of lny invention as stated, Vconstituting thenature thereof, I provide a further port or communication, d, inconjunction with one of the inlet-ports-say, lil-(see dotted lines,Figs. l and 2,) the purpose of this port being to adlnit steam to opsideof, the cylinder, as shown inl Figs. 1, 2, 3, the plunger D being tocontrol the further admission of steam to steam-chest; hence the fartherport d1, (shown is Fig. 1,) and communicating from plunger-cylinder tosteam- N0.`172,603, datedJanuary 25, 1876; application filed July26,1875.'

chest. The steam in the chest has a further communication by a port, d2,to the cylinder that contains the'plunger D'. (Shown clearly in Fig. 1.)

' By this means direct steam-connection from boiler is had to operatethe plungers D D',

these being connectedby the lever E, as shown in Figs. 1 and 3. Theleverage can be established or regulated by means of a movable fulcrum,E', which, as l1ere`shown,slides 011 a horizontal bar, e, Fign, althoughother ordi nary Ways ofchanging the fulcrum can be used. The areas ofthe plungers are dissimilar; thus, as shown, that of D is smaller thanthat of D', in order to obtain unequal pressures, and to effect thepurpose of my improvement, as will hereinafter appear.

My improvement being thus constructed and arranged, the operation oftheparts is as follows: Supposing the position of the valve to be as inFig. l, the steam is admitted through inlet-port b and port b2 under thecore cl of the valve; thence into main steam-port b5 to drive the pistonto complete a stroke, the exhaust taking place through the opposite mainport b4 under the center core c2 of valve, from thence out of exhaust.At same time, be it noted, the direct pressure of steam from boiler hasentered the inlet-.port b1, and, by means lof the Vport d, raised thesmall plunger D, and in doing so passes through the port d1 into thesteam-chest top of the valve. The excess of steam-pressure top of valve,owing to its increased area, passes through the port cl2 and raises thelarge plunger D', and in so doing, by means of the lever-connection withplunger D, causes it to close further admission of steam to the chest.The fulcruin having been supposed at center, it is plain that thus thesteam-pressure top of the valve becomes less to that degree that thesteam-pressure under the valve is the greaten -z'. e., the less pressureof steam top of valve With its increased area, being, therefore,counterbalanced by the greater steam-pressure under the valve actingupon less area, causes said valve to be automatically balanced, andrelieved of its friction.

In case` the steam-pressure in the steamchest becomes reduced fromcondensation or other causes, then-the small plunger, on -account ofthegreater pressure below the valve, will be forced up, and thus supplythe -chest through port d1 With its loss ot' pressure. It the pressureunder the valve C becomes reduced and a greater pressure is in thesteamchest, then the larger plunger will be forced up, to permit suchexcess of pressure to escape through the exhaust-port d3. (See Fig. l.)This done, said plunger will also close. A greater pressure in thesteam-chest can be achieved for the purpose ot a pressure-valve, bysliding` or changing the fulcrum inthe direction of the large'plunger.(See Figs. 1 and 3.) The excess of leverage will then be in fz vor ofsmall plunger, and this raised admits the required greater pressure insteam-chest. f

My improvement, therefore, enables the valve to be balanced or to act asa pressure-valve, or be overbalanced, (by changing the fulcrum in thedirection. of the small p1unger,)

and all this While the engine is in motion, .the engineer having thevalve under perfect control.

By changing the positionl of the fulcrum all Wear that takes place canbe compensated, or follow up whatever increase ot' area arisesfroin use;also, the s't'eam-chestfcan be reedfrom all dirt, grit, and impuritiesout of the exhaust d3, and otherwise my improvement possesses advantagesreadily apparent.

. What I claim isl. A lever having a changeable fulcrum, and carryingplungers arranged in a steam-chest with relation to a slide-valve, invthe manner herein shown and described, and by means whereof the lesserpressure top of valve is counterbalanced by the greater pressure belowsaid valve, forming an improved balanced valve, as set forth.

2. The combination of the plungers D D, le-

ver E, movable fnlcrum E', ports d2 cll d, with relation to asteam-chest and cylinder A, to operate as and forthe purpose set forth.In testimony' of said invention I have hereunto set my hand.' v

BENJAMIN BRAZELLE. Witnesses: v

WILLIAM W. HERTHEL, CHAs. F. MEIsNnR.

